I think the whole issue of transitions while traveling vs transitions in the classroom setting is comparing apples to oranges - I have three different kids with three different personalities and they are all over the board on transitioning, but traveling even when we've had to wait for hours due to cancelled flights etc has never been a transition issue... because we're usually going someplace fun, plus it's different and it's not school.
I agree with the posters above who mention that although a teacher isn't allowed to (or qualified to) make a diagnosis, there is good reason to pay attention to what the teacher has said is going on with your child - the teacher is spending a good deal of your child's day with them, and seeing them in an environment that you aren't (usually) seeing them function in as well as seeing many many other children function in the same type of situation. It's possible that the behaviors the teacher is seeing are due to gifted quirkiness but otoh the teacher may be seeing something else entirely.
Our ds' 2nd grade teacher tried over and over again to tell us she felt she was seeing signs of ADHD in our ds (or possibly IQ low enough he wasn't able to handle the classwork). We *knew* our ds was extremely high IQ both from living with him and from previous testing, so we immediately put off her concerns to a combination of teacher not liking him, classwork being too boring, visual-spatial thinking, and gifted quirky behaviors. Eventually we found out we were really, really, really wrong - ds has a relatively severe disability which was impacting him at school, and like Dee Dee, we wish we'd been open to what the teacher said the minute she first mentioned something - ds' previous teachers had also noticed signs of it and simply let him slide by because they realized he was very very smart. DS is *fine* and a-ok, but it would have been tremendously helpful to him (and to us) to have known earlier in his academic days that he was struggling and that we could have put accommodations and tutoring in place to help him out.
Chances are, with most kids, it's just gifted quirkiness - but there's still a chance that the teacher is seeing something beyond that. Looking into the possibility of something else isn't going to cause any problems and will at least give you data to take back to this or any other teachers who are tempted to suggest something is up in the future; overlooking something when there are signs is something you may later regret.
Best wishes,
polarbear
